1. Field of the Invention
The present invention regards an agricultural machine comprising:
a body equipped with at least one working component; PA1 a connecting mechanism allowing connection of said agricultural machine to a tractor, said connecting mechanism being connected to said body by a first joint with an upwardly directed axis; PA1 an operating device for pivoting the connecting mechanism with respect to said body around the axis of said first joint, said connecting mechanism being positionable in at least two working positions; PA1 transmission elements for powering said at least one working component, said transmission elements comprising at least one gearbox connected to the body by a second joint with an upwardly directed axis; and PA1 a control mechanism for pivoting said gearbox with respect to the body around the axis of said second joint wherein the gearbox is positionable in operating positions that correspond to said working positions of the connecting mechanism. PA1 a first control cylinder installed between the connecting mechanism and the body, and PA1 a second control cylinder installed between the body and the gearbox and connected in series to the first control cylinder. PA1 the operating cylinder is a dual-action cylinder; PA1 the transmission elements comprise at least one telescopic transmission shaft with universal joints connected to the input shaft of the gearbox; PA1 said at least one transmission shaft or at least one of said transmission shafts is supported by the connecting mechanism; PA1 the transmission elements receive the movement of the power take-off shaft of the tractor vehicle to which the agricultural machine is intended to be connected; PA1 the body rests on the ground by means of at least one wheel, and the connecting mechanism consists of a drawbar connected to the midsection of said body; PA1 the body comprises a chassis to which the connecting mechanism is connected and in which is (are) suspended the working component(s) by means of a suspension device that makes it possible for it (them) to move with respect to the chassis in order to adapt to the ground terrain.
2. Discussion of the Background
An agricultural machine is described in document EP 0 277 343 A1 and comprises a mower-conditioner. First, this known machine comprises a body that consists of a chassis that moves over the ground via two wheels, and a harvesting device suspended in the chassis by means of a drawn deformable quadrilateral suspension device. This known machine also includes a drawbar allowing it to be connected to a tractor. This drawbar is connected to the midsection of the chassis by means of a joint whose axis is roughly vertical so that it can occupy at least two working positions by pivoting around said axis. The harvesting device itself comprises a carrying structure carrying cutting drums and a conditioning rotor installed behind them.
This known machine additionally comprises transmission elements designed to power the cutting drums and the conditioning rotor. These transmission elements consist primarily of a transmission device installed in the front part of the drawbar that is designed to receive the movement from the power take-off shaft of the tractor via a first telescopic transmission shaft with universal joints. These transmission elements also consist of a gearbox connected to the carrying structure of the harvesting mechanism by means of a joint whose axis is roughly parallel to the axis of the joint connecting the drawbar to the chassis. This gearbox receives the movement of the transmission device output shaft via a second telescopic transmission shaft with universal joints. The output shaft of the gearbox transmits the movement to the drive components of the harvesting device.
The axis of the joint connecting the gearbox to the carrying structure of the harvesting mechanism is located in the vertical plane pointing in the direction of displacement and enclosing the axis of the joint connecting the drawbar to the chassis, and is located in front of this latter axis. As a result, it is possible to swivel said gearbox around the axis of its joint when the drawbar is pivoted into its various positions so that the input shaft of the gearbox is always pointing towards the front of the drawbar. To this end, this known machine comprises a control mechanism that consists of a coupling. This coupling comprises a first forked coupling that is guided in rotation between the two universal joints of the second telescopic transmission shaft and a second forked coupling mounted on the gearbox and inside which the input shaft of said gearbox is guided in rotation. These two forked couplings are connected to each other by a joint with an approximately horizontal axis that passes through the center of the universal joint of the second telescopic transmission shaft located beside the input shaft of the gearbox.
In this known machine, the position of the gearbox is controlled via the second telescopic transmission shaft in response of the swiveling of the drawbar. Additionally, the joint connecting the two forked couplings enables the harvesting mechanism to move with respect to the chassis in order to adjust to the ground terrain.
The control mechanism used on this known machine has several disadvantages. It first requires a special telescopic transmission shaft with universal joints since the first forked coupling is guided in rotation thereon by means of two bearings. Assembly then requires that relatively strict machining tolerances be observed since the axis of the joint connecting the two forked couplings together must pass precisely through the center of the universal joint of the second telescopic transmission shaft located beside the input shaft of the gearbox.
U.S. Pat. No. 5,272,859 presents another mower-conditioner comparable to the one described in EP 0 277 343 A1. The control mechanism, which is designed to pivot the gearbox to position it properly according to the position of the drawbar, is made up of a telescopic control rod located between the drawbar and the gearbox. This telescopic control rod comprises an inner section connected to the drawbar by means of a ball and socket joint and capable of sliding inside an outer section connected indirectly to the gearbox. At its end beside the gearbox, the outer section of the telescopic control rod has two lugs between which extends a rigid tubular housing that is part of the gearbox. Said lugs are connected to the said housing by means of a joint with a roughly horizontal axis that passes through the center of the universal joint of the second telescopic transmission shaft located next to the gearbox.
In this known machine, the position of the gearbox is controlled via the telescopic control rod in response of pivoting of the drawbar. Moreover, the fact that the telescopic control rod can lengthen and shorten combined with the pivoting enabled by the joint connecting said rod to the gearbox allows the harvesting mechanism to move with respect to the chassis in order to adapt itself to the ground.
In order to allow the inner section to slide easily inside the outer section, it is necessary to provide sufficient play between these two sections. Under these conditions, absorption of the driving torque applied to the gearbox causes the telescopic control rod to bend. This can slow the shortening of the telescopic control rod during the harvesting mechanism's adjustment to the ground contours. Additionally, the lengthening and shortening of the telescopic control rod under a large load risks causing relatively rapid wear of said rod.
EP 0 678 237 A1 describes a mower that primarily comprises a body consisting of a chassis that moves over the ground via two wheels and a cutting mechanism suspended from the chassis by means of a suspension device that allows the cutting mechanism to move with respect to said chassis in order to adapt itself to the ground contours. This mower also has a drawbar making it possible to connect it to a tractor. This drawbar is connected to the mid-section of the chassis by means of a joint with an approximately vertical axis so that it can occupy at least two working positions by swiveling around said axis.
This known mower also comprises transmission elements designed to power the cutting tools. These transmission elements consist first of all of an upper gearbox mounted on the drawbar and whose input shaft receives the motion of the output shaft of a transmission device installed in the front part of the drawbar via a telescopic transmission shaft with universal joints. The output shaft of this upper gearbox extends in a roughly parallel fashion to the axis of the joint connecting the drawbar to the chassis. This output shaft is coaxial with the input shaft of the lower gearbox, whose output shaft is connected to the drive components of the cutting mechanism via another telescopic transmission shaft with universal joints.
The lower gearbox is thus borne by the upper gearbox so that it is capable of swiveling around the common axis of the output shaft of the upper gearbox and the input shaft of the lower gearbox. During pivoting of the drawbar, the position of the lower gearbox is controlled by a guiding mechanism. In a first embodiment, this guiding mechanism consists of a rod installed between the lower gearbox and the cutting mechanism, roughly parallel to the transmission shaft connecting the output shaft of said lower gearbox to the drive components of the cutting mechanism. In a second embodiment, the guiding mechanism consists of a deformable parallelogram connected to the chassis.
In this known mower, the position of the lower gearbox is controlled via the upper gearbox during the swiveling of the drawbar. This solution is relatively expensive since it requires two gearboxes capable of pivoting with respect to each other.